Depends on what sort of outfit you are working for, and what you are building. A lot of CEMs are doing Flying Probe or ICT on the boards ahead of investing time building into units or adding parts that prevent access to rework. We have a combination of strategies depending on what we are building.
AOI is enough for a lot of our automotive PCBAs until an end combined ICT & functional test before going out of the door, but we build millions and there are no issues.
However, we also build complex, high accuracy assemblies that, even with preselection of components have build up of tolerance issues, so flying probe and or ICT gives us a list to swap out. Other units can have upto 20 pcbas in, so these are batch tested when built, before going into final assembly.
reply »